1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Weight, Gravitational Force

  1. Dec 4, 2009 #1
    1. The problem statement, all variables and given/known data

    A mass weighs 20 N at the surface of a planet of 3000 km radius. What is the mass's weight when it is in orbit 3000 km above the surface of the planet?

    2. Relevant equations
    F = (Gm1m2)/r2 (well... not really)
    Ug = mgy

    3. The attempt at a solution
    I don't even know. I'm trying to find the g on this planet but I'm not sure where that would lead me... Help please >_<
  2. jcsd
  3. Dec 4, 2009 #2


    User Avatar
    Homework Helper

    what is the new 'r' you want to find? How does that relate to the original 'r'?

    r= r at surface then

    GMm/r2= ?
  4. Dec 4, 2009 #3
    yeah, i just needed to write the equations out instead of just thinking in my head

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook